From 41ea916ab231bad450a4b46cbb6a6ccace3d0372 Mon Sep 17 00:00:00 2001
From: Stefan Collier <stefan.collier@electriccarscheme.com>
Date: Thu, 5 Dec 2024 18:29:03 +0000
Subject: [PATCH 1/2] Add GB National Insurance Numbers aka ID Numbers

In GB, we use [national insurance numbers](https://www.gov.uk/national-insurance/your-national-insurance-number) as our primary citizen identification numbers.

These are 9 digit strings that are typically 2 alpha characters followed by 6 numbers and finally a single alpha. There are few combinations are not permitted [as seen here](https://www.gov.uk/hmrc-internal-manuals/national-insurance-manual/nim39110).

The `valid` code provided will produce a subset of all legal NI numbers. A regex in the locale file to produce all combinations isn't necessary.
---
 lib/locales/en-GB.yml     |  3 +++
 test/test_en_gb_locale.rb | 14 ++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/lib/locales/en-GB.yml b/lib/locales/en-GB.yml
index 96aaa2992e..01d667d8f1 100644
--- a/lib/locales/en-GB.yml
+++ b/lib/locales/en-GB.yml
@@ -85,6 +85,9 @@ en-GB:
         - Northern Ireland
       default_country_code:
         - GB
+    id_number:
+      valid: '/[A-CEGHJ-NOPR-TW-Z][ACEHJLMOPRSW][0-9]{6}[ABCD]/'
+      invalid: '/(BG|GB|NK|KN|TN|NT|ZZ)[0-9]{6}[E-Z]{1}/'
     internet:
       domain_suffix:
         - co.uk
diff --git a/test/test_en_gb_locale.rb b/test/test_en_gb_locale.rb
index d12cf30cb9..099295cbca 100644
--- a/test/test_en_gb_locale.rb
+++ b/test/test_en_gb_locale.rb
@@ -69,4 +69,18 @@ def test_en_gb_postcode_outcode_is_valid
     assert_match(/^[A-PR-UWYZ][A-HK-Y0-9]/, outcode)
     assert_match(/\w{1,2}\d{1,2}|\w\d[ABCDEFGHJKPSTUW]|\w\w\d[ABEHMNPRVWXY]/, outcode)
   end
+
+  def test_en_gb_id_number_valid_is_valid
+    id_code = Faker::IdNumber.valid
+
+    assert_equal(9, id_code.length)
+    assert_match(/^[A-CEGHJ-PR-TW-Z][A-CEGHJ-NPR-TW-Z][0-9]{6}[A-DFM]$/, id_code)
+  end
+
+  def test_en_gb_id_number_invalid_is_invalid
+    id_code = Faker::IdNumber.invalid
+
+    assert_equal(9, id_code.length)
+    assert_not_match(/^[A-CEGHJ-PR-TW-Z][A-CEGHJ-NPR-TW-Z][0-9]{6}[A-DFM]$/, id_code)
+  end
 end

From ca11234772cd58d65c9a0257e8467979ef711c8c Mon Sep 17 00:00:00 2001
From: Stefan Collier <stefan.collier@electriccarscheme.com>
Date: Wed, 8 Jan 2025 18:14:08 +0000
Subject: [PATCH 2/2] Document en-GB Faker::IdNumber locale intricacies

---
 doc/default/id_number.md | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/doc/default/id_number.md b/doc/default/id_number.md
index 89216c0279..2f34871b01 100644
--- a/doc/default/id_number.md
+++ b/doc/default/id_number.md
@@ -50,3 +50,25 @@ Faker::IdNumber.danish_id_number(gender: :female) #=> "050390-9980"
 # Generate a valid French Social Security number (INSEE number)
 Faker::IdNumber.french_insee_number #=> "22510589696868"
 ```
+
+## ID Number and Locales
+Besides the locale-specific ID Number methods. Faker supports retrieving localised calls to `.valid` and `.invalid`. 
+Here is an example:
+
+```ruby
+Faker::Config.locale = 'fr-FR'
+Faker::IdNumber.valid #=> "22510589696868"
+```
+
+Locales with specific intricacies are as such:
+
+### en-GB
+When provided with British English, unformatted'[National Insurance](https://www.gov.uk/national-insurance/your-national-insurance-number)' numbers are generated. 
+Note: Faker can only generate a subset of all possible legal/illegal national insurance numbers.
+
+```ruby
+Faker::Config.locale = 'en-GB'
+Faker::IdNumber.valid #=> "AJ405924A"
+Faker::IdNumber.invalid #=> "BG316764W"
+```
+